Tape Automated Bonding (TAB) is a process that is used to interconnect a chip to a package. The TAB process involves bonding an integrated circuit (IC) device to a patterned metal on a polymer tape which typically consists of copper foil on a polyimide tape. Once the IC device is bonded to the tape the apparatus is commonly referred to as a Tape Carrier Package (TCP).
FIGS. 1A and 1B illustrate a top and side view of a typical prior art TCP 10, respectively. As shown in FIGS. 1A and 1B, the frontside of an integrated circuit device 12 is secured to the polyimide tape 18. The tape 18 is secured within a plastic housing/carrier 22 which provides structural support to the TCP. Bond pads 14 on the frontside of the integrated circuit device are bonded to copper leads 16 formed on the polyimide tape 18. The copper on the polyimide tape 18 is patterned to form the electrically conductive leads 16 which are used for power, ground, and signal distribution between IC device 12 and a substrate, such as a printed circuit board (PCB). Test pads 20 are provided along the outer periphery of TCP 10 to facilitate the electrical testing of IC device 12 before the TCP is shipped to the customer. A plastic encapsulant 26 covering the frontside surface 23 of device 12 provides protection to bond pads 14 and the frontside (active side) surface of the device. Alignment holes 28 in tape 18 facilitate the alignment of test pads 20 with the corresponding electrical interface structure of a test device (not shown).
The present invention is aimed at removing heat from the surface(s) of an integrated circuit device that is housed within a TCP during the functional testing of the integrated circuit device. The functional test is performed before a package is mounted to a printed circuit board. The purpose of the test is to check the functionality and to monitor the electrical performance of the integrated circuit. The environmental test is generally performed within a temperature controlled chamber. A vacuum pickup chuck is typically used to position the package within the chamber. The electrically testing of the integrated circuit is performed by positioning the package within the chamber such that the package contacts are in electrical contact with a corresponding set of contacts located on a contactor of a test apparatus. Information pertaining to the electrical performance of the device is gathered during the test. The information is then used to screen out bad devices and to classify the integrated circuits according to their operating frequency. This process is commonly referred to as "binning out."
It is commonly known that as the temperature of an integrated circuit rises, the frequency at which the device operates decreases. Therefore, it is important to control the temperature of the integrated circuit during the functional test to ensure that the device is appropriately separated or "binned" according to its operating frequency. It is also important to control the temperature of the integrated circuit since excessive temperatures may affect the performance of the circuit and cause permanent degradation of the device. In addition, it is desirable to hold the temperature of the integrated circuit device at a relatively constant temperature throughout the testing sequence.
The traditional method for cooling integrated devices within a TCP has been through convection heat transfer. Using this method, heat is dissipated from the integrated circuit through the outer surfaces of the device into still or moving air. As the integration level (i.e., the number of transistors per device) of integrated circuits increases, or the power requirements, or the operating speed of these integrated circuits increases, the amount of heat generated by these devices increases to a point where conventional convection based solutions are inadequate. This poses a particular problem when testing integrated circuit devices housed within TCPs due to the extremely low thermal mass of the package. If the integrated circuit device is not adequately cooled during the test, and is permitted to rise significantly above a designated test temperature, the device may be unnecessarily downgraded into a lower frequency bin. It is also important that the temperature of the integrated circuit device be maintained above the designated test temperature during the functional test sequence in order to ensure that the device is not improperly upgraded into a higher frequency bin.
Thus, what is needed is an apparatus and method for controlling the temperature of an integrated circuit device that solves the problems associated with testing a TCP.